The study also showed that those who were dependent on indoor tanning were more likely to have started tanning at an earlier age, be concerned about their appearance, and have depressive symptoms.

Federal data show that the percentage of all U.S. adults reporting using a UV-emitting indoor tanning device at least once in the past 12 months decreased from 5.5 percent in 2010 to 3.5 percent in 2015. However, usage varies among different groups of U.S. adults. The most common users are non-Hispanic women ages 18 to 29, with 20.4 percent reporting indoor tanning at least once in the past 12 months.

Prior research indicates that indoor tanning can be a problematic behavior for some young women similar to other forms of addiction, said Darren Mays, PhD, MPH, the lead author of the study.

"If we are to reduce this risky behavior and ultimately reduce skin cancer risks, we must understand what factors—such as behaviors, beliefs, and psychological comorbidities—are associated with indoor tanning dependence," continued Dr. Mays, who is an assistant professor at Georgetown University Medical Center in Washington, D.C., and a member of the Cancer Prevention and Control Program at the Georgetown Lombardi Comprehensive Cancer Center.

To understand more about indoor tanning dependence and the factors associated with it in young adult, non-Hispanic white women, Dr. Mays and his colleagues looked at answers to online questionnaires completed by 389 non-Hispanic white women ages 18 to 30 who had used an indoor tanning device one or more times in the prior 12 months.

Indoor tanning dependence was assessed using two questionnaires modified from screeners for other addictive behaviors, the CAGE and Diagnostic and Statistical Manual for Mental Disorders (DSM) screeners. To be classed as dependent on indoor tanning, individuals had to screen positive on both modified questionnaires.

Overall, 22.6 percent of participants screened positive for indoor tanning dependence. In bivariate analysis, those who screened positive were more likely to have started tanning at an earlier age, be concerned about their appearance, and have depressive symptoms.

Further analysis showed that indoor tanning dependence was strongly associated with beliefs about physical appearance and depressive symptoms. As women’s beliefs that appearance is important grew stronger, they were 73 percent more likely to screen positive for indoor tanning dependence. Women who screened positive for depressive symptoms were almost four times as likely to screen positive for indoor tanning dependence than those who did not have depressive symptoms.

"Our study has identified a subgroup of young adult women who are dependent on indoor tanning," concluded Dr. Mays. "These young women are unlikely to respond to public health messaging and we will need to develop a more intensive resource to motivate behavior change. Given that we found strong associations between indoor tanning dependence and beliefs about physical appearance and psychological comorbidities like depression, these intensive behavior-modification resources likely need to address these co-occurring psychological concerns."

There is very little research in the area of developing and testing interventions to address indoor tanning dependence, so we may need to draw from successful approaches to changing behaviors like cigarette smoking, said Dr. Mays.

According to Dr. Mays, the main limitation of the study is that he and his colleagues analyzed indoor tanning dependence in a group of young women from a single geographic area, the Washington, D.C., metropolitan area. Thus, the findings may not be the same for the entire population or other groups, such as young men.